[Urban High Martial Arts] [Summoned Beasts] [One Female Lead] [Beast Fusion]
Lu Ming transmigrates into a novel he had read, becoming a summoner whom everyone looks down on.
But against all odds, he awakens an immensely powerful talent.
From then on, his summoned beasts can fuse and rank up.
Garurumon, covered head to toe in steel; the Devouring Demon Lord, like Venom, able to possess others and change its form; the terrifying pet beast Ghost Queen, capable of wiping out an entire city; the Spirit King, formed by fusing multiple spirits...
Thus, Lu Ming embarks on a path to crush the whole world with his summoned beasts.
I'll give you four stars for your single heroine first.